2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/100039The aim of this article is to show, how computer algebra can be used when applying Liu's procedure. Although Mathematica (a commercial product by Wolfram Research Inc.) is used, it is possible to use other computer algebra systems as well.11 pages, 1 figure extended introduction, some minor correctionsComputational Physicstext